1. Field of the Invention
The present invention relates to bearing mounts. More particularly, the present invention relates to a simplified adjustment assembly which interacts between a bearing assembly and the housing within which the bearing assembly is supported. Specifically, the present invention relates to an assembly by which to effect incremental adjustments to the axial end play of, or the preload on, the outer race of a bearing assembly, either alone or in a set.
2. Description of Related Art
With journal arrangements for which thrust loading is not reasonably anticipated, and within which cylindrical bearings are appropriate to support radial loading, it is customary to utilize some structure by which to effect axial retention of the bearings that rotatably support a shaft, or the like. The shaft may apply a reasonable thrust load on the bearing, such that the bearing will remain seated within the housing. When the environment in which the Journal arrangement is employed is such that both radial and thrust loading is expected, one generally considers the use of tapered bearing sets because they create excellent rotational support for a shaft subjected to such loading without impairing rotation of the shaft. However, other alternatives are often employed because of difficulties heretofore experienced in adjusting the axial end play of, or the preload on, the races which support the rollers in a tapered bearing assembly.
Thrust loading is transferred by the individual bearing assemblies from the shaft to the journal box or housing. Generally, the inner race of each bearing assembly abuts a shoulder on the rotatable shaft. The outer race similarly abuts an opposed shoulder on the housing in which the bearing is supported. The structure, which presents the opposed shoulders between which the bearing set is captured, must permit assembly of the shaft and both bearing assemblies into the housing. Moreover, even if opposed, rigid shoulders could be provided, such an arrangement would not allow for any variation or adjustment in the end play of, or the preloading applied to, the bearing set.
It is, however, difficult to achieve and maintain incremental adjustments of the small magnitude desired by using a nut threaded onto the end of the shaft. Nuts are often crenelated to permit a safety wire or clip to be inserted through a diametric bore in the shaft in order to secure the selected position of the nut. However, the magnitude of the adjustments permitted by the aforesaid arrangement is limited to a function of the thread pitch and the number of crenelations as well as their angular disposition.
To accomplish incremental adjustments of a small or fine magnitude, a variety of arrangements have been developed which utilize shims interposed between one race of the bearing set and a bearing retainer. The shims utilized by such prior art assemblies are available in a plurality of dimensions so that the selection of appropriately sized shims will generally achieve the desired end play or preloading. However, the installation of a typical shim assembly generally requires a rather complicated series of steps. For example, one must normally measure the gap between one race of the bearing assembly and the bearing retainer to determine the size of the shim or shims required, and the shim or a combination of shims must then be selected. The selected shim(s) must then be appropriately inserted between the selected race of the bearing assembly and the bearing retainer. The installation is not concluded until a final measurement has been made to verify that the proper end play and preloading has been achieved.
The installation of prior known shim assemblies is, therefore, a relatively complicated process for which considerable expertise is required, and for which shims must be available in a wide variety of sizes in order for the desired end play or preloading to be effected. Another form of a prior art bearing adjusting assembly employs opposed cams or ramps. The use of cams or ramps allows for a wide range in the amount of end play or preloading adjustment available and reduces the number of components which must be stocked. However, the locking means heretofore employed in conjunction with cams or ramps to secure the selected adjustment, generally comprises a plurality of bolts or other locking tabs that are receivable within bores. The need to provide threaded bores, however, creates a problem in that discrete placement of threaded bores to receive the bolts severely restricts usage of the array to that permitted by the particular placement of the bores.
It is a primary object of the present invention to provide a simplified assembly by which to effect incremental adjustments to the end play of, and the preload on, a bearing set.
It is another object of the present invention to provide an adjusting assembly, as above, which incorporates a relatively uncomplicated arrangement by which to secure the selected end play and preload, by moving the bearing race upon which the adjusting assembly acts through dimensional increments.
It is a further object of the present invention to provide an adjusting assembly, as above, which does not require stocking a plurality of different size shims.
It is still another object of the present invention to provide an adjusting assembly, as above, which assures that the selected end play and preloading will be maintained, and which can thereafter be further adjusted as necessary or desired, with relative ease.
The objectives of the present invention are achieved by an adjustable thickness bearing preload assembly comprising a first thrust ring with indexing teeth, a second thrust ring without indexing teeth, and an indexing spring. The thrust rings are formed with ramped surfaces and are assembled side-by-side with the ramped surfaces facing each other. By rotating one thrust ring with respect to the other, the combined thickness of the rings will increase or decrease due to the ramping action. The indexing spring is essentially a stamped circular ring with indexing pawls projecting from the flat surface. The pawls engage the indexing teeth on the first thrust ring. When the indexing spring is rotated relative to the thrust ring, the pawls will deflect and ride over the thrust ring indexing teeth. When rotation is reversed, the pawls engage the thrust ring teeth and prevent reverse rotation.
By attaching the indexing spring to the thrust ring without teeth, the two thrust rings can be rotated in one direction relative to each other to increase the thickness, but will not reverse direction due to pawl-to-tooth contact.
Assembly of the two thrust rings and indexing spring is simplified when compared to the conventional preload assemblies. The indexing spring is positioned in the counterbore of the toothless thrust ring with pawls facing outward. The outer diameter of the indexing spring is notched to prevent rotation relative to the thrust ring. The toothed thrust ring is then positioned over the indexing spring to complete the assembly of the shim. The indexing spring remains trapped between the two thrust rings. The angular adjustment resolution can be fine-tuned y varying the number of indexing spring pawls and the thrust ring teeth.
These and other objects of the invention, as well as the advantages thereof over existing and prior art forms which will be apparent in view of the following detailed specification, are accomplished by means hereinafter described and claimed.